Chediak-Higashi syndrome (CHS) and Hermansky-Pudlak syndrome (HPS) are fatal human genetic disorders characterized by structural and functional defects of multiple cytoplasmic organelles -- melanosomes, lysosomes, and granules. We have cloned the genes for both CHS and HPS and are currently preparing antisera to the corresponding proteins. We wish to define the ina-acellular location of the CHS and BPS proteins (which are entirely novel), in both normal and mutant cells, and to determine whether these proteins interact with each other and with other cellular components. We will immunostain fissue samples using our antisera and determine cellular localization of CHS and HPS using the confocal microscope at the MM. These studies should help elucidate the pathogenesis of these disorders and thus guide eventual design of rational therapies. SCIENTIFXC SUBPROJECT GRANT NUMBER: P41RR00570-27